Probably one of the most13 common forms of escapes is the comment.
Start a comment. Everything to the end of the input line is ignored.
This may sound simple, but it can be tricky to keep the comments from interfering with the appearance of the final output.
If the escape is to the right of some text or a request, that portion of
the line is ignored, but the space leading up to it is noticed by
gtroff. This only affects the
and its variants.
One possibly irritating idiosyncracy is that tabs must not be used to line up comments. Tabs are not treated as whitespace between the request and macro arguments.
A comment on a line by itself is treated as a blank line, because after eliminating the comment, that is all that remains:
Test \" comment Test
To avoid this, it is common to start the line with
causes the line to be treated as an undefined request and thus ignored
Another commenting scheme seen sometimes is three consecutive single
''') at the beginning of a line. This works, but
gtroff gives a warning about an undefined macro (namely
''), which is harmless, but irritating.
To avoid all this,
gtroff has a new comment mechanism using the
\# escape. This escape works the same as
\" except that
the newline is also ignored:
Test \# comment Test
Ignore all input until
gtroff encounters the macro named
.end on a line by itself (or
.. if end is not
specified). This is useful for commenting out large blocks of text:
text text text... .ig This is part of a large block of text that has been temporarily(?) commented out. We can restore it simply by removing the .ig request and the ".." at the end of the block. .. More text text text...
text text text… More text text text…
Note that the commented-out block of text does not cause a break.
The input is read in copy-mode; auto-incremented registers are affected (see Auto-increment).